Here's a place where I can post my thoughts on new papers, provide updates on my projects, and post info that will eventually be on my website The Theropod Database - http://theropoddatabase.com/ . It will center on theropods, but may delve into other topics as well such as phylogenetics.

Tuesday, October 5, 2010

But this C. longicollis syntype isn't Cloelophysis

Again, something I noticed while cataloging past Coelophysis diagnoses. Back in 1887, Cope noted that what would be named Coelophysis (Coelurus longicollis and bauri at the time) differs from Anchisaurus (his Megadactylus) and Megalosaurus in lacking an ectocondylar tuber on the femur. This is also mentioned as a diagnostic character in his 1889 note naming Coelophysis. This caught my eye since I had just dealt with ectocondylar tubers for Kayentavenator. So I checked Huene's (1906, 1915) papers describing and illustrating the original Coelophysis material, and indeed the complete syntype femur of C. longicollis (AMNH 2704) lacks an ectocondylar tuber. This is unlike theropods (or shuvosaurids, which C. bauri syntype femur AMNH 2725 was referred to by Nesbitt et al., 2007), but is similar to silesaurids like Silesaurus and Eucoelophysis. Also like silesaurids but unlike theropods, the femoral head is parallelogram-shaped instead of distinctly offset. Rather unsurprisingly, it seems to have autapomorphies of the contemporaneous Eucoelophysis (after Ezcurra, 2006)- no trochanteric shelf, reduced fourth trochanter.

This underscores the fact Cope's original Coelophysis material can't be assumed to be a single taxon. We now have Coelophysis bauri (cervical AMNH 2701), Eucoelophysis baldwini (femur AMNH 2704), Shuvosauridae (femur AMNH 2725), Dromomeron romeri (femur AMNH 2721- Nesbitt et al., 2009) and Parasuchia (teeth AMNH 2733- Padian, 1986). Yet it also shows that some of the material IS diagnostic, people just have to bother actually examining it.

The cervical referrable to Coelophysis bauri which I discussed in the last post is the lectotype of longicollis. Again, it's funny how wrong Hunt and Lucas were that it didn't matter which syntype they chose for a lectotype, since they were all supposedly undiagnostic. Though really the cervical is the best lectotype because Cope's diagnosis for the species is based on it, as is the name itself.

And yes, Longosaurus longicollis' lectotype is an ilium chosen by Welles (1984) which is not viable as a lectotype for C. longicollis since it was not one of Cope's syntypes. So Welles intended for Longosaurus to be a new genus for C. longicollis but goofed.